Peripheral Blood Mononuclear Cells In Presence Research Articles

Gingival fibroblasts produce paracrine signals that affect osteoclastogenesis in vitro

In periodontitis, gingival fibroblasts (GF) appear to produce a multitude of paracrine factors. However, the influence of GF-derived soluble factors on osteoclastogenesis remains unclear. In this case study, production of paracrine factors by GF was assessed under inflammatory and non-inflammatory conditions, as well as their effect on osteoclastogenesis. Human primary GF were cultured in a transwell system and primed with a cocktail of IL-1β, IL-6 and TNF-α to mimic inflammation. GF were co-cultured directly and indirectly with human peripheral blood mononuclear cells (PBMC). Cytokines and chemokines in supernatants (flow cytometry based multiplex assay), osteoclastogenesis (TRAcP staining) and gene expression (qPCR) were quantified on days 7 and 21.Results from this case study showed that GF communicated via soluble factors with PBMC resulting in a two-fold induction of osteoclasts. Reversely, PBMC induced gene expression of IL-6, OPG and MCP-1 by GF. Remarkably, after priming of GF with cytokines, this communication was impaired and resulted in fewer osteoclasts. This could be partly explained by an increase in IL-10 expression and a decrease in MCP-1 expression. Intriguingly, the short priming of GF resulted in significantly higher expression of inflammatory cytokines that was sustained at both 7 and 21 days.GF appear to produce paracrine factors capable of stimulating osteoclastogenesis in the absence of physical cell-cell interactions. GF cultured in the presence of PBMC or osteoclasts had a remarkably inflammatory phenotype. Given profound expression of both pro- and anti-inflammatory cytokines after the inflammatory stimulus, it is probably the effector hierarchy that leads to fewer osteoclasts.

2D STATIC AND 3D DYNAMIC CO-CULTURES OF HUMAN BONE MARROW MESENCHYMAL STEM CELLS AS NOVEL IN VITRO BIOENGINEERED MYOGENIC MODELS

Spontaneous muscle regenerative potential is limited, as severe injuries incompletely recover and result in chronic inflammation. Current therapies are restricted to conservative management, not providing a complete restitutio ad integrum; therefore, alternative therapeutic strategies are welcome, such as cell-based therapies with stem cells or Peripheral Blood Mononuclear Cells (PBMCs). Here, we described two different in vitro myogenic models: a 2D perfused system and a 3D bioengineered scaffold within a perfusion bioreactor. Both models were assembled with human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and human primary skeletal myoblasts (hSkMs) to study induction and maintenance of myogenic phenotype in presence of PBMCs. When hBM-MSCs were cultured with human primary skeletal myoblasts (hSkMs) in medium supplemented with 10 ng/mL of bFGF; cells showed increased expression of myogenic-related gene, such as Desmin and Myosin Heavy Chain II (MYH2) after 21 days, and a prevalent expression of anti-inflammatory cytokines (IL10, 15-fold). Next, PBMCs were added in an upper transwell chamber and hBM-MSCs significantly upregulated myogenic genes throughout the culture period, while pro-inflammatory cytokines (e.g., IL12A) were downregulated. In 3D, hBM-MSCs plus hSkMs embedded in fibrin-based scaffolds, cultured in dynamic conditions, showed that all myogenic-related genes tended to be upregulated in the presence of PBMCs, and Desmin and MYH2 were also detected at protein level, while pro-inflammatory cytokine genes were significantly downregulated in the presence of PBMCs. In conclusion, our works suggest that hBM-MSCs have a versatile myogenic potential, enhanced and modulated by PMBCs. Moreover, our 3D biomimetic approach seemed to better resemble the tissue architecture allowing an efficient in vitro cellular cross-talk.

Immune-infiltrated kidney organoid-on-chip model for assessing T cell bispecific antibodies

T cell bispecific antibodies (TCBs) are the focus of intense development for cancer immunotherapy. Recently, peptide-MHC (major histocompatibility complex)-targeted TCBs have emerged as a new class of biotherapeutics with improved specificity. These TCBs simultaneously bind to target peptides presented by the polymorphic, species-specific MHC encoded by the human leukocyte antigen (HLA) allele present on target cells and to the CD3 coreceptor expressed by human T lymphocytes. Unfortunately, traditional models for assessing their effects on human tissues often lack predictive capability, particularly for "on-target, off-tumor" interactions. Here, we report an immune-infiltrated, kidney organoid-on-chip model in which peripheral blood mononuclear cells (PBMCs) along with nontargeting (control) or targeting TCB-based tool compounds are circulated under flow. The target consists of the RMF peptide derived from the intracellular tumor antigen Wilms' tumor 1 (WT1) presented on HLA-A2 via a bivalent T cell receptor-like binding domain. Using our model, we measured TCB-mediated CD8+ T cell activation and killing of RMF-HLA-A2-presenting cells in the presence of PBMCs and multiple tool compounds. DP47, a non-pMHC-targeting TCB that only binds to CD3 (negative control), does not promote T cell activation and killing. Conversely, the nonspecific ESK1-like TCB (positive control) promotes CD8+ T cell expansion accompanied by dose-dependent T cell-mediated killing of multiple cell types, while WT1-TCB* recognizing the RMF-HLA-A2 complex with high specificity, leads solely to selective killing of WT1-expressing cells within kidney organoids under flow. Our 3D kidney organoid model offers a platform for preclinical testing of cancer immunotherapies and investigating tissue-immune system interactions.

Contribution of peripheral blood mononuclear cells isolated by advanced filtration system to myogenesis of human bone marrow mesenchymal stem cells co-cultured with myoblasts

BackgroundContribution of peripheral blood mononuclear cells (PBMCs) in myogenesis is still under debate, even though blood filtration systems are commonly used in clinical practice for successfully management of critic limb ischemia. ObjectivesA commercial blood filter used for autologous human PBMC transplantation procedures is characterized and used to collect PBMCs, that are then added to well-established 2D in vitro myogenic models assembled with a co-culture of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and skeletal myoblasts (hSkMs) whit the aim of investigating their potential contribution to stem cell myogenic commitment. MethodsA commercial blood filter was physically and chemically studied to understand its morphological characteristics and composition. PBMCs were concentrated using this system, further isolated by Ficoll-Paque density gradient centrifugation, and then added in an upper transwell chamber to a 2D co-culture of hBM-MSCs and hSkMs. Myogenic commitment was investigated by RT-PCR, immunofluorescence, and flow cytometry immunophenotyping. Cytokine levels were monitored by ELISA assay in culture media. ResultsThe blood filtration system was disassembled and appeared to be formed by twelve membranes of poly-butylene terephthalate fibers (diameters, 0.9–4.0 μm) with pore size distribution of 1–20 μm. Filter functional characterization was achieved by characterizing collected cells by flow cytometry. Subsequently, collected PBMCs fraction was added to an in-vitro model of hBM-MSC myogenic commitment. In the presence of PBMCs, stem cells significantly upregulated myogenic genes, such as Desmin and MYH2, as confirmed by qRT-PCR and expressed related proteins by immunofluorescence (IF) assay, while downregulated pro-inflammatory cytokines (IL12A at day 14) along the 21 days of culture. NoveltyOur work highlights chemical-physical properties of commercial blood filter and suggests that blood filtrated fraction of PBMC might modulate cytokine expression in response to muscle injury and promote myogenic events, supporting their clinical use in autologous transplantation.

Zinc aspartate induces proliferation of resting and antigen-stimulated human PBMC under high-density cell culture condition

BackgroundZinc, one of the most important essential trace elements in the human body, regulates a wide range of cellular functions of immune cells, such as proliferation, differentiation and survival. Zinc deficiency affects both the innate and adaptive immune system. Zinc supplementation was discussed as possible therapy for infectious diseases and T cell-mediated autoimmune diseases. However, the influence of commercial zinc preparations on proliferation and cytokine production of resting and antigen-stimulated peripheral blood mononuclear cells (PBMC) has not yet been completely investigated. MethodsHere, we examined whether zinc aspartate (Unizink®), an approved drug to treat zinc deficiency in patients, induces proliferation, cytokine production, and induction of apoptosis/caspase 3/7 activity of resting PBMC under high-density cell culture condition. In addition, we performed antigen-specific proliferation experiments, where PBMCs of healthy donors vaccinated against Influenza A (H1N1) and/or SARS-CoV-2 were stimulated with Influenza A (H1N1) peptides or SARS-CoV-2 peptides as well as the Mixed Lymphocyte Culture (MLC) in the presence of increasing concentrations of zinc aspartate. ResultsWe observed a dose-dependent enhancement of proliferation and induction of cytokine production (IFN-γ, IL-5, GM-CSF and CXCL10) of resting PBMC in presence of zinc aspartate. The number of cells with active caspase 3/7 and, consecutively, the amount of cells undergoing apoptosis steadily decreased in presence of zinc aspartate. Moreover, zinc aspartate was capable of stimulating antigen-specific PBMC proliferation using MLC or influenza A (H1N1) and SARS-CoV-2 peptides in both a dose-dependent and a donor-specific manner. In the absence of zinc aspartate, we clearly could discriminate two groups of responders: low and high responders to antigenic stimulation. The addition of increasing concentration of zinc aspartate significantly stimulated the proliferation of PBMC from low responders, but not from high responders. ConclusionTaken together, our results suggest that zinc aspartate induces the proliferation of resting and antigen-stimulated PBMCs under high-density cell culture conditions. Thus, zinc might represent a supportive treatment in patients suffering from infectious diseases.

Peripheral blood mononuclear cells contribute to myogenesis in a 3D bioengineered system of bone marrow mesenchymal stem cells and myoblasts.

In this work, a 3D environment obtained using fibrin scaffold and two cell populations, such as bone marrow-derived mesenchymal stem cells (BM-MSCs), and primary skeletal muscle cells (SkMs), was assembled. Peripheral blood mononuclear cells (PBMCs) fraction obtained after blood filtration with HemaTrate® filter was then added to the 3D culture system to explore their influence on myogenesis. The best cell ratio into a 3D fibrin hydrogel was 1:1 (BM-MSCs plus SkMs:PBMCs) when cultured in a perfusion bioreactor; indeed, excellent viability and myogenic event induction were observed. Myogenic genes were significantly overexpressed when cultured with PBMCs, such as MyoD1 of 118-fold at day 14 and Desmin 6-fold at day 21. Desmin and Myosin Heavy Chain were also detected at protein level by immunostaining along the culture. Moreover, the presence of PBMCs in 3D culture induced a significant downregulation of pro-inflammatory cytokine gene expression, such as IL6. This smart biomimetic environment can be an excellent tool for investigation of cellular crosstalk and PBMC influence on myogenic processes.

Zoledronate promotes inflammatory cytokine expression in human CD14-positive monocytes among peripheral mononuclear cells in the presence of γδ T cells.

Bisphosphonates distributed to bone exert toxic effects specifically towards osteoclasts. On the other hand, intravenous administration of a nitrogen-containing bisphosphonate (N-BP) such as zoledronate induces acute-phase reactions (APRs), including influenza-like fever 1day later, indicating an interaction with immunocompetent cells circulating blood. Although it has been reported that activation of γδ T cells is pivotal to induce an APR following treatment with zoledronate, downstream events, including the production of inflammatory cytokines after activation of γδ T cells, remain obscure. We investigated the effects of zoledronate on inflammatory cytokine expression in human peripheral blood mononuclear cells (PBMCs) in vitro. While zoledronate induced mRNA expressions of tumour necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6 and interferon-γ (IFN-γ) in PBMC, depletion of γδ T cells abolished that zoledronate-induced expression of those cytokines, indicating the necessity of γδ T cells for expression induction by zoledronate. However, which types of cells were responsible for the production of those cytokines in blood remained unclear. As it is generally accepted that monocytes and macrophages are primary sources of inflammatory cytokines, CD14+ cells from PBMC were exposed to zoledronate in the presence of PBMC, which resulted in induced expression of mRNAs for IL-1β, IL-6 and IFN-γ, but not for TNF-α. These results indicate that CD14+ cells are responsible, at least in part, for the production of IL-1β, IL-6 and IFN-γ in blood exposed to zoledronate. This suggests that CD14+ cells play an essential role in the occurrence of APRs following N-BP administration.

Abstract 5570: Identification of novel mechanisms of resistance against the redirection of T-cell effector function for cancer therapy

Abstract In the recent times the way to tackle cancer has been broadly expanded to new opportunities, being the immunotherapy the spearhead of this revolution. Two of the different novel strategies to boost the immune response against tumor cells are the T Cell Bispecific antibodies (TCBs) and the Chimeric Antigen Receptors (CARs), both able to redirect the T cells of the host against the tumor cells. While the TCBs consist of an engineered antibody that binds both to a tumor associated antigen and a T cell receptor, activating it; the CARs consist of a modified T cell that exhibit the binding site to the antigen fused to the intracellular signaling motifs that activate the T cell. Clinical evidence shows that either TCBs or CARs are effective to treat cancer. These can be directed to a vast variety of tumor antigens. Some examples are the HER2-TCB, directed against the HER2 receptor tyrosine kinase overexpressed in 20% of the breast cancers. However, the therapeutic effectivity in tumors is lower than expected and the mechanisms of resistance to these promising immunotherapies have not been explored yet. Therefore, there is a need to anticipate them. In this project, we have developed a immunoresistant model against HER2-TCB, by using the HER2+ breast cancer cell line BT474 as a model. To generate immunoresistant cells, cells were exposed with the TCBs and peripheral blood mononuclear cells (PBMCs) for several months in order to obtain resistance. Indeed, these resistant cells were resistant also in a 3D organoid model and in an in vivo humanized PBMC model. Furthermore, these resistant cells were also resistant to a CAR expressing HER2. Interestingly, a cytokine array that assess more than 80 cytokines did not show a dramatic change in the secretome of resistant cells, in basal conditions and in presence of PBMCs and HER2-TCB, suggesting that the mechanism of resistant is intrinsic on the resistant cells. In addition, these resistant cells did not lose the expression of the antigen (HER2). Therefore, we aimed to identify intrinsic mechanisms of resistance by means of RNA-seq. Although we did not identify the cause of the resistance yet, transcriptomic analysis showed a dramatic change between sensitive and resistant cells, with more than 50 genes acutely up-or downregulated in resistant cells (≥4-fold; p < 10-5). Gene set enrichment analysis identified numerous differences in biological processes between both populations. In parallel, we have also generated the very same model in vivo, with serial passagues in humanized PBMC mice treated with HER2-TCB. The next step will be to identify the mechanism of resistance by gain and loss of function approaches and to validate it in a cohort of human samples and in our collection of Patient Derived Xenografts. In conclusion, we have generated an interesting resistant model to immunotherapies that can be used as a tool to identify unknown mechanisms of resistance and with potential clinical applications that will reinforce the use of immunotherapy in the clinics. Citation Format: Enrique Javier Arenas Lahuerta, Alex Martínez-Sabadell, Irene Rius Ruiz, Beatriz Morancho, Macarena Román, Cristina Bernadó, Joaquín Arribas. Identification of novel mechanisms of resistance against the redirection of T-cell effector function for cancer therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5570.

Immunophenotyping Reveals No Significant Perturbation to PBMC Subsets When Co-cultured With Colorectal Adenocarcinoma Caco-2 Cells Exposed to X-Rays.

In vitro co-culture models between tumor cells and peripheral blood mononuclear cells (PBMCs) allow studying the interplay between these cell populations, potentially gaining insight into the in vivo response of the immune system to the presence of the tumor, as well as to possible other agents as radiation used for therapeutic purposes. However, great care is needed in the experimental optimization of models and choice of conditions, as some setups might offer a limited possibility to capture subtle immune perturbations. A co-culture model of PBMCs from healthy donors and colorectal adenocarcinoma Caco-2 cells was successfully adopted in a previous work to measure effects on Caco-2 and modulation of signaling when these latter are irradiated. We here tested if the same experimental setting allows to measure perturbations to the main PBMC subsets: we performed immunophenotyping by means of flow cytometry and quantified helper and cytotoxic T cells, NK cells, and B cells, when PBMCs are cultured alone (control), in presence of non-irradiated Caco-2 cells or when these latter are exposed to a 10 Gy X-ray dose from a conventional radiotherapy accelerator. To measure a baseline response in all experimental conditions, PBMCs were not further stimulated, but only followed in their time-evolution up to 72 h post-irradiation of Caco-2 and assembly of the co-culture. In this time interval PBMCs maintain a high viability (measured via the MTT assay). Caco-2 viability (MTT) is slightly affected by the presence of PBMCs and by the high radiation dose, confirming their radioresistance. Immunophenotyping results indicate a large inter-individual variability for different population subsets already at the control level. We analyzed relative population changes and we detected only a small but significant perturbation to cytotoxic T cells. We conclude that this model, as it is, is not adequate for the measurements of subtler immune perturbations (if any, not washed-out by inter-individual differences). For this purpose, the model needs to be modified and further optimized e.g., including a pre-treatment strategy for PBMCs. We also performed a pooled analysis of all experimental observations with principal component analysis, suggesting the potential of this tool to identify subpopulations of similarly-responding donors.

1679-P: Islet Autoimmunity in Adults with Impaired Glucose Tolerance (IGT) and Newly Diagnosed, Treatment-Naïve Type 2 Diabetes (NDX T2D) in the Restoring Insulin Secretion (RISE) Study

In obesity, immune cells establish a systemic inflammatory state associated with development of insulin resistance and T2D. Previous studies have shown that peripheral blood mononuclear cell (PBMC) responses to islet proteins (IPs) in adults with established T2D on glucose-lowering therapies identify those patients with more severe β-cell dysfunction. Moreover, attenuation of PBMC responses to IPs in adults with established T2D improves β-cell function. However, the presence of IP reactive PBMCs, glutamic acid decarboxylase autoantibodies (GADA), and their relationship to insulin sensitivity and β-cell function has never been evaluated in IGT or Ndx T2D. We measured at baseline and after 12 months of RISE medication interventions (12 months with either metformin or liraglutide plus metformin or for 3 months with insulin glargine followed by 9 months of metformin), PBMC responses to IPs, GADA, insulin sensitivity, and β-cell function in 258 RISE participants (mean ± SD) 53.3 ± 9.2 years of age, BMI 35.1 ± 5.4 kg/m2, with IGT (n=180) or Ndx T2D (<12 months duration, n=78). At baseline, IP reactive PBMCs were present in 46% of participants with IGT and 40% of participants with Ndx T2D. However, 97% of IGT and 98% of Ndx T2D were GADA negative. There were no significant relationships between the presence of PBMC reactivity to IPs, GADA positivity and insulin sensitivity or β-cell function. RISE treatments did not alter PBMC responses to IPs, GADA, or the relationship between IP reactive PBMCs or GADA with glycemic responses. In summary, IP reactive PBMCs are present in a large percentage of adults with very early dysglycemia, However, the presence of IP reactive PBMCs did not correlate with insulin sensitivity or early β-cell dysfunction. Further studies are needed to unravel the pathogenesis of IP reactive PBMCs and GADA and their effects on β-cell function during progression of T2D. Disclosure B. Brooks-Worrell: None. A.H. Tjaden: None. S. Edelstein: None. B.M. Palomino: None. K. Utzschneider: Other Relationship; Self; Medtronic. S.A. Arslanian: Research Support; Self; National Institutes of Health. Other Relationship; Self; AstraZeneca, Eli Lilly and Company, Novo Nordisk Inc. K.J. Mather: Research Support; Self; Abbott, Merck & Co., Inc., Novo Nordisk Inc., Sanofi. T.A. Buchanan: None. K.J. Nadeau: None. K.M. Atkinson: None. E. Barengolts: None. S.E. Kahn: Advisory Panel; Self; Boehringer Ingelheim International GmbH, Eli Lilly and Company, Intarcia Therapeutics, Janssen Scientific Affairs, LLC., Merck & Co., Inc., Novo Nordisk A/S, Pfizer Inc. J.P. Palmer: None. Funding National Institutes of Health (R01DK107560)

In vitro Interaction of Pseudomonas aeruginosa Biofilms With Human Peripheral Blood Mononuclear Cells.

The human immune cell response against bacterial biofilms is a crucial, but still poorly investigated area of research. Herein, we aim to establish an in vitro host cell-biofilm interaction model suitable to investigate the peripheral blood mononuclear cell (PBMC) response to Pseudomonas aeruginosa biofilms. P. aeruginosa biofilms were obtained by incubating bacteria in complete RPMI 1640 medium with 10% human plasma for 24 h. PBMC obtained from healthy donors were added to preformed P. aeruginosa biofilms. Following a further 24 h incubation, we assessed (i) PBMC viability and activation; (ii) cytokine profiles in the supernatants; and (iii) CFU counts of biofilm forming bacteria. Cell-death was <10% upon 24 h incubation of PBMC with P. aeruginosa biofilms. PBMC incubated for 24 h with preformed P. aeruginosa biofilms were significantly more activated compared to PBMC incubated alone. Interestingly, a marked activation of CD56+CD3− natural killer (NK) cells was observed that reached 60% of NK cells as an average of different donors. In the culture supernatants of PBMC co-cultured with P. aeruginosa biofilms, not only pro-inflammatory (IL-1β, IFN-γ, IL-6, and TNF-α) but also anti-inflammatory (IL-10) cytokines were significantly increased as compared to PBMC incubated alone. Furthermore, incubation of biofilms with PBMC, caused a statistically significant increase in the CFU number of P. aeruginosa, as compared to biofilms incubated without PBMC. In order to assess whether PBMC products could stimulate the growth of P. aeruginosa biofilms, we incubated preformed P. aeruginosa biofilms with or without supernatants obtained from the co-cultures of PBMC with biofilms. In the presence of the supernatants, the CFU count of biofilm-derived P. aeruginosa, was two to seven times higher than those of biofilms incubated without supernatants (P < 0.01). Overall, the results obtained shed light on the reciprocal interaction between human PBMC and P. aeruginosa biofilms. P. aeruginosa biofilms induced PBMC activation and cytokine secretion but, in turn, the presence of PBMC and/or PBMC-derived components enhanced the number of P. aeruginosa biofilm associated bacteria. This may indicate a successful bacterial defensive/persistence strategy against immune response.

Levels of CXCL10 Chemokine in Dengue Infected Hepatocyte Huh 7 it-1 Cell Line Co-cultured with Peripheral Blood Mononuclear Cells

Dengue is a mosquito borne virus that spreads rapidly in the world. At present, it is estimated that more than 3.9 billion people are at risk of being infected with dengue virus (DENV) and there are 96 million clinical cases that have been reported annually in 128 countries worldwide. In DENV infected patients often associated with liver dysfunction which hepatocyte and kuppfer cells as the main target of viral infections. DENV infection induced the expression of several chemokines, which might play an important role during the inflammatory response and pathogenesis of a disease. CXCL10 is known as a chemokine that activates lymphocytes for innate and adaptive immunity, induces tissue damage, and modulates tumor formation. Therefore, we conducted an in vitro study using Huh 7it-1 cells co-cultured with peripheral blood mononuclear cells (PBMCs) to investigate CXCL10 chemokine induction during DENV infection. Huh 7it-1 cells were grown on 96 micro well plate until a monolayer was formed. The cells were infected with DENV-2 at an MOI of 0.5 FFU/cell and 1 FFU/cell in the presence of PBMCs. Heat inactivated DENV-2 and Huh7 cell medium were used as control. After 2 hours of infection, cells were co-cultured with PBMCs and incubated at 37 oC with 5% CO 2 for 48 h. Cell supernatant was collected and CXCL10 chemokine levels were measured using CXCL10 Quantikine ELISA Kit. Statistical analysis was performed by SPSS 23. In the presence of PBMCs, CXCL10 levels from DENV infected Huh 7it-1 at an MOI of 0,5 FFU/cell and MOI of 1 FFU/cell were 552,653 ± 22,779 pg mL-1 and 576,787 ± 16,901 pg mL-1 . Those levels were higher when compared with supernatan from heat inactivated DENV-2 and control cells. Without PBMCs, all of treatments showed lower level of CXCL10. DENV-2 infection in Huh 7it-1 cells co-cultured with PBMCs was able to induce CXCL10 secretion. Furthermore, heat inactivated DENV-2 also still capable to inducen the secretion of CXCL10 chemokine in Huh 7it-1 cells.

Trastuzumab upregulates expression of HLA-ABC and T cell costimulatory molecules through engagement of natural killer cells and stimulation of IFNγ secretion

ABSTRACT It is increasingly recognized that trastuzumab, an antibody approved for treating human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer, exerts some of its antitumor effects through enhanced T cell responses. Full activation of CD8+ T cells requires both expression of major histocompatibility complex class I molecules (HLA-ABC) and expression of the T cell costimulatory molecule CD80 or CD86; however, the impact of trastuzumab treatment on the expression of HLA-ABC and CD80 and CD86 has not been investigated in HER2-overexpressing breast cancer cells. In this study, we found that, while there is no direct correlation between the expression of HER2 and HLA-ABC in breast cancer, knockdown of HER2 or inhibition of HER2 kinase by lapatinib downregulated HLA-ABC expression. Trastuzumab had no meaningful effects on HLA-ABC expression in HER2-overexpressing breast cancer cells in monoculture; however, treatment of such cells with trastuzumab in co-culture with human peripheral blood mononuclear cells (PBMC) significantly upregulated not only HLA-ABC expression but also CD86 expression. We showed that this upregulation was mediated by interferon gamma (IFNγ) secreted from the natural killer (NK) cells in PBMC as a result of engagement of NK cells by trastuzumab. We further confirmed this effect of trastuzumab in vivo using a mouse mammary tumor model transduced to overexpress human HER2. Together, our data provide evidence that trastuzumab upregulates expression of HLA-ABC and T cell costimulatory molecules in HER2-overexpressing breast cancer cells in the presence of PBMC, which supports the view that T-cell-mediated immune responses are involved in trastuzumab-mediated antitumor effects.

Abstract A91: BGB-283 exhibits potentials in enhancing tumor immune sensitization and lymphocyte function

Abstract Oncogenic B-RAF, which drives cell transformation and proliferation, has been detected in a variety of human malignancies. Prior studies suggested that B-RAF-targeting therapies could increase antigen expression, decrease immune suppressive factors in tumor microenvironment, and improve homing of T effector cells to the tumors. Thus, selective BRAF inhibitors were suggested to possess immunosensitization properties and could be used in combination with immunotherapies to achieve more durable disease control/response in treating BRAF V600E melanomas. BGB-283 is a novel inhibitor of the RAF dimer with potent and reversible inhibitory activities against RAF family kinases including wild type A-RAF, B-RAF, C-RAF and B-RAF V600E. In addition, BGB-283 has potent inhibitory activity against EGFR (Mol. Can. Ther. onlinefirst 2015; doi: 10.1158/1535-7163). BGB-283 is currently under Phase 1 clinical investigations. In the present study, BGB-283 showed significant stimulation of melanocyte-differentiation antigens and HLA-A expression in BRAF V600E melanoma cell lines. Intermediate level of BGB-283 was found to stimulate proliferation of human peripheral blood mononuclear cell (PBMC) and isolated human CD4+ and CD8+ T cells. In addition, BGB-283 potentiated IFNγ releasing from PBMCs at concentration range of 30∼300 nM. In newly developed the 3D tumor spheroid/PBMC co-culture system, BGB-283 improved PBMC function as measured by cell proliferation and IFNγ production. The presence of PBMC also enhanced the anti-proliferation activity of BGB-283 on A375 BRAF V600E mutant melanoma cells in the co-culture system. Further studies have shed light on the mechanistic underpinning of the immunomodulation effect of BGB-283 and its potential differentiation from vemurafenib. These findings support BGB-283 as a promising clinical stage antitumor drug that could potentially combine with immunotherapies by enhancing immune sensitization and T cell function. Citation Format: Xi Yuan, Mi Lian, Xiaoran Wu, Lusong Luo. BGB-283 exhibits potentials in enhancing tumor immune sensitization and lymphocyte function. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A91.

Protein-bound polysaccharide-K augments the anticancer effect of fluoropyrimidine derivatives possibly by lowering dihydropyrimidine dehydrogenase expression in gastrointestinal cancers

Protein-bound polysaccharide-K (PSK) enhances the antitumor effect of anticancer drug when used clinically in combination with such drugs. PSK is known to act by immune-mediated mechanisms; however, the relationship between PSK and metabolic enzymes of anticancer drugs is unknown. We used the collagen gel droplet-embedded culture drug sensitivity test (CD-DST) clinically to evaluate the sensitivity of anticancer drugs. In the present study, we modified the CD-DST by adding peripheral blood mononuclear cells (PBMCs) (immuno-CD-DST) and examined the antitumor effect of PSK in combination with anticancer drugs. First, HCT116 human colon cancer cells were cultured with PSK and 5-fluorouracil (5-FU) or 5'-deoxy-5-fluorouridine (5'-DFUR) in the presence or absence of PBMCs, and the antiproliferative effects were compared. In the presence of PBMCs, PSK augmented the inhibitory effects of 5-FU and 5'-DFUR on HCT116 cell proliferation. Next, using human gastric cancer and colon cancer cell lines, the effects of PSK on mRNA expression of various metabolic enzymes of fluoropyrimidines: dihydropyrimidine dehydrogenase (DPD), thymidylate synthase, thymidine phosphorylase and orotate phosphoribosyl transferase, were examined by real-time PCR. PSK significantly enhanced DPD mRNA expression in all of the cancer cell lines tested, but not those of the other enzymes. Addition of IFN-α and TRAIL, cytokines known to inhibit DPD expression, to the cultures reduced DPD mRNA expression in the cancer cells. When PBMC samples collected from healthy volunteers were cultured with PSK, IFN-α mRNA expression increased in 3 of the 5 PBMC samples, while TRAIL mRNA expression was unchanged. The present results propose the possibility that PSK induces PBMCs to express IFN-α which inhibits DPD expression, and consequently augments the antitumor effect of 5-FU or 5'-DFUR. Immuno-CD-DST is useful for evaluating drugs with immunological mechanisms of action.

Abstract A35: Immunological characterization of Imprime PGG® and an anti-EGFR antibody combination treatment for cancer

Abstract More promising antitumor strategies utilize combination therapies, with each strategy targeting a separate aspect of oncogenesis. Imprime PGG® (Imprime PGG) is a soluble beta-1,3/1,6 glucose polymer being developed as an adjunct to monoclonal antibody (MAb) therapy for cancer. Imprime PGG, a pathogen- associated molecular pattern isolated from the cell wall of S. cerevisiae, has shown therapeutic antitumor and survival-enhancing effects when combined with an antitumor MAb in several in vivo syngeneic and xenogeneic tumor models. Here, we evaluated and characterized the antitumor activity and functional synergy of Imprime PGG in combination with an anti-EGFR MAb, cetuximab, in two different cancers, using an EGFR+ human pancreatic tumor line, MiaPaCa-2, and an EGFR+ human ovarian tumor line, SKOV-3. The objectives of this study were: (1) Evaluate the ability of cetuximab to activate complement as measured by iC3b opsonization on tumor cells (measured by flow cytometry using a FITC anti-human iC3b MAb); (2) Characterize tumor cells for expression of the complement regulatory proteins (CRP) CD46, CD55 and CD59 (measured by flow cytometry using fluorescently-labeled CRP-specific antibodies); (3) Evaluate tumor cytolysis following treatment with cetuximab +/- Imprime PGG in the absence and presence of human peripheral blood mononuclear cells (PBMC) (using the MTT colorimetric assay); and (4) Assess the ability of cetuximab +/- Imprime PGG to induce cytokines when tumor cells were cultured with human PBMC. Key findings include: (1) in vitro cetuximab does not induce iC3b deposition on SKOV-3 and MiaPaCa-2 tumor cells over that seen with fresh serum alone. (2) Both tumor cell lines expressed all CRPs but each to a variable extent. (3) Cetuximab did not induce CDC but did induce ADCC in the presence of PBMC, and Imprime PGG further enhanced cetuximab-induced cytolysis under these conditions. (4) The combination of cetuximab and Imprime PGG inhibited the secretion of VEGF in tumor cell/PBMC co-cultures compared to levels observed with either agent alone. These studies demonstrate antitumor synergy of Imprime PGG when combined with cetuximab that may be mediated by modulation of the tumor microenvironment. Overall, the data indicate synergy between Imprime PGG and cetuximab in vitro in inducing antitumor activity in both pancreatic and ovarian tumor cells and provide rationale for such combination strategy for therapy in cancer. Citation Information: Clin Cancer Res 2010;16(14 Suppl):A35.

Osteogenic differentiation of human mesenchymal stromal cells is promoted by a leukocytes containing fibrin matrix

Mesenchymal stem cells (multipotent human mesenchymal stromal cells, MSC) are currently the most promising cell type for regenerative medicine. For a clinical approach, it is necessary to develop and establish methods for expansion, differentiation, and delivery. A completely autologous plasma clot containing peripheral blood mononuclear cells (PBMC) was tested for the osteopromotive activity towards expanded human mesenchymal stem cells in vitro. The plasma clot was prepared from anticoagulated blood plasma after addition of isolated leukocytes and calcium chloride. Plasma clots after the gelation were added to subconfluently growing MSC or used in a transwell system. Cell proliferation, the activity of alkaline phosphatase, the release of osteoprotegerin, C-terminal procollagen peptide, as well as osteocalcin, the analysis of matrix mineralization as well as bone nodule formation were analyzed up to 3 weeks. In contrast to plasma clots with no exogenously added leukocytes, the presence of PBMC within the plasma clot significantly promoted osteogenic differentiation of MSC correlated to the time period of incubation. Proliferation of MSC was decreased at maximal mineralization time points. In addition, the osteopromotive activity was identified as soluble factor/factors by transwell assay system. There was a decrease in osteoprotegerin when the cells were cultured in the presence of plasma clots compared to control cell cultures without plasma clots. The osteocalcin expression was continuously higher after culture in the presence of plasma clots and significantly higher after 2- and 3-week after culture in the presence of leukocyte-containing plasma clots compared to 1-week cell culture. Differences in the concentration of the C-terminal procollagen peptide were not measured. The direct inoculation of an autologous mononuclear cell fraction (which contains leukocytes and MSC), e.g., isolated from a bone marrow aspirate or a different source into an autologous plasma gel, may be a further new strategy for bone fracture therapy.

Cytokines and chemokines released from the interaction of anti-HER2/anti-CD3 bispecific antibody armed activated T cells (ATC) with the tumor microenvironment can induce efficient antigen presentation and induce an adaptive immune response

3072 Background: The tumor microenvironment has a complexes network of soluble factors, and cell surface signals which can induce a significant state of immune tolerance. Several immunotherapy strategies attempted to break this tolerance aiming to re-activate and expand tumor specific adaptive immune responses. Our approach uses ATC armed with chemically heteroconjugated bispecific antibodies (AATC) that bind and activate T cells while targeting Her2/neu on tumor targets. This creates non-HLA restricted cytotoxic/cytokine producing-T lymphocytes. Methods: Coculture experiments were perform by mixing AATC with Her2/neu+ SKBR3 target cell lines and fresh autologous peripheral blood mononuclear cells (PBMC) to induce cytotoxic activity directed at SKBR3 after 7 days. The ability of PBMCs to develop an adaptive response towards SKBR3 at the end of 7 days was studied using standard 51Cr release assay. Chemokines and cytokines released form the above interaction were studied. Results: In the presence of PBMC and SKBR3 cells, armed ATC induced the secretion of IFNγ, GM-CSF, IL-12, and MIP1α after 96 hrs of co-culture compared to unarmed ATC co- cultured with SKBR3 and PBMC. When we irradiated AATC so that they can induce initial tumor cell kill and die shortly after, we noticed the emergence of SKBR3 specific CD8 CTL response 7 days later. Depletion of CD14+ cells from the co-culture at day 0 reduced the SKBR3 CTL response at day 7 as well as the amounts of the cytokines generated (96 hrs) significantly. When supernatants from a 24 h co-culture of armed ATC+ PBMC+ SKBR3 were mixed with fresh CD14+ monocytes and autologous CD3+ T cells for 7 days, there was a significant increase in SKBR3 specific CTL activity compared to supernatants from co-cultures of unarmed ATC, PBMC, and SKBRR3. Studies are on there way to evaluate the impact of these cytokines on the phenotype CD14+ monocytes. Conclusions: These results suggest that cytokines and chemokines released from the interaction of AATC with the tumor microenvironment can induce an efficient maturation of immature antigen presenting cells and may lead ultimately to breaking tolerance. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Transtarget Inc. Transtarget Transtarget

Cytokine-mediated effects of peripheral blood mononuclear cells from patients with atopic eczema on keratinocytes (HaCaT) in a new coculture system.

Interactions between keratinocytes and mononuclear cells via cytokines and adhesion molecules are thought to play a crucial part in inflammatory skin diseases. The cytokine-mediated effects of peripheral blood mononuclear cells (PBMC) from patients with atopic eczema (AE) and healthy individuals on keratinocytes (HaCaT) were investigated in vitro. A new coculture model (Transwell system) which consists of a lower and an upper compartment, which are separated by a polycarbonate-treated membrane, was established. 3[H]thymidine incorporation of keratinocytes and lymphocytes, as well as IL-6, IL-8 and IFN-gamma synthesis, were measured. Keratinocyte proliferation was significantly enhanced in the presence of PBMC from patients with AE. In contrast, PBMC from normal donors did not enhance HaCaT cell proliferation when they were cocultured. Lymphocytes from patients with AE showed a significantly enhanced proliferation after coculture with keratinocytes. However, PBMC from normal donors did not proliferate in the presence of HaCaT cells. Keratinocyte supernatants incubated with PBMC from either atopic or normal volunteers induced a suppression of lymphocyte 3[H]thymidine incorporation. In supernatants from cocultures of PBMC from patients with AE and keratinocytes, significantly enhanced amounts of IL-6 and IL-8, compared with normal donor's lymphocytes and HaCaT cells, were measured. No differences in IFN gamma production were observed. When PBMC were cultured without HaCaT cells, supernatants contained equal levels of IL-6, IL-8 and IFN-gamma in normal donors and in patients with AE. Interestingly, HaCaT cells spontaneously secrete measurable amounts of IL-6, IL-8 and IFN-gamma. Blocking experiments with neutralizing antibodies against these interleukins showed a complete inhibition of keratinocyte proliferation when PBMC from normal donors were used whereas the proliferative potency of PBMC supernatants from patients with AE on keratinocytes remained. Our data indicate that (i) PBMC from patients with AE stimulate keratinocyte proliferation via soluble factor(s) that are different from IL-6, IL-8 and IFN-gamma; (ii) probably, HaCaT cells spontaneously produce lymphocyte/monocyte inhibitory soluble factors and IL-6, IL-8 as well as IFN-gamma; and (iii) secretion and/or activity of keratinocyte-derived inhibitory mediators is regulated via cytokines of PBMC infiltrating inflammatory skin.

The Role of Interleukin-1β in Direct and Toll-Like Receptor 4-Mediated Neutrophil Activation and Survival

The regulation of systemic and local neutrophil activation is crucial to the clearance of infections and the successful resolution of inflammation without progress to tissue damage or disseminated inflammatory reactions. Using purified lipopolysaccharide (pLPS) and highly purified neutrophils, we have previously shown that Toll-like receptor 4 signaling is a potent neutrophil activator, but a poor stimulator of survival. In the presence of peripheral blood mononuclear cells (PBMCs), however, pLPS becomes a potent neutrophil survival factor. Interleukin (IL)-1beta has been identified as an important neutrophil activator and prosurvival cytokine, and is produced in abundance by LPS-stimulated PBMCs. We now show that IL-1beta fails to activate highly purified neutrophils or enhance their survival, but in the presence of PBMCs, IL-1beta induces neutrophil survival. We hypothesized that LPS-primed neutrophils might become responsive to IL-1beta, but were unable to demonstrate this. Moreover, IL-1ra failed to prevent pLPS + PBMC-dependent neutrophil survival. In studies of IL-1R1(-/-) mice, we found that LPS was still able to mediate neutrophil survival, and neutrophil survival was enhanced by the addition of monocytic cells. Thus an important paradigm of neutrophil regulation needs to be viewed in the context of a cellular network in which actions of IL-1beta on neutrophils are indirect and mediated by other cells.